Unit 1 Engine Operating Principles and Engine Construction

1. Part A Engine Overall Mechanics Unit 1 Engine Operating Principles and Engine Construction Part B The Four-Stroke Engine Part C Engine Noise Diagnosis Part D Dialogue New words Phrases and Expressions

2. Engine Overall Mechanics The engine is the source of power that makes the wheels go around and the car move. The automobile engine is a machine that turns heat energy of fuel into mechanical energy for moving the vehicle. Because fuel is burned within the engine, it is also called for internal-combustion engine. The burning of gasoline inside the engine produces high pressure in the engine combustion chamber. This high pressure forces piston to move, the movement is carried by connecting rods to the engine crankshaft. The crankshaft is thus made to rotate; the rotary motion is carried through the power train to the car wheels so that they rotate and the car moves.

3. Engine Overall Structure

4. Engine Overall Mechanics Piston Crank Mechanism Valve mechanism Fuel System Ignition System Starting System Cooling System Lubricating System

5. The Four –Stroke Engine Four-Stroke-Cycle Gasoline Engine Four-Stroke-Cycle Diesel Engine

6. Engine Noise Diagnosis Piston slap is a very common noise most noticeable when an engine is cold. A piston that slaps against the cylinder wall produces a hollow, muffled, bell-like sound, quite audible when an engine is operating under load at low rpm. (12)Piston slap results from worn pistons or cylinders, collapsed piston skirts, excessive piston-to-cylinder wall clearance, misaligned connecting rods, or a lack of lubricating oil. Therefore, in order to correct piston slap, it will be necessary to replaced or resize the pistons, rebore the cylinder or replace the sleeves, replace or realign the rods, or add oil to the engine.

7. Engine Noise Diagnosis The one abnormal sound unrelated to worn, damaged, loose, or maladjusted engine parts is detonation knock. The noise is most noticeable during acceleration with the engine under load and operating at normal temperature. Excessive detonation is very harmful to the engine, and you should do everything possible to correct the cause as soon as possible. Detonation knock in an engine is usually the product of advanced ignition timing, excessive carbon buildup in the combustion chambers, or use of too low an octane fuel. (15) To correct this malfunction, check the distributor's advance mechanisms , check and reset the ignition timing adjustment, decarbonize the engine , or recommend a change in fuel to one with a higher octane rating certificate.

8. Dialogue A: Hello! Welcome to Blue Sky Automobile Company, can I help you? B: I want to buy a car, could you introduce some new model? A: Ok, I'd like to show you the new model, 2008 Buick Lacrosse. B: Oh, it looks nice. A: yes, I bet you’ll like it more after my introduction. It’s unique RES(Remote Engine Start) permit you start the engine 50 miles away, and the AC(Air Conditioning) which has been set consequently start work. So you will feel very comfortable when you access the car. B: Very good. Could you tell me more about the specifications of this model?

9. Dialogue A: Sure. As you can see it's of deluxe body style with Black exterior, 2.4 Liter V6 engine. B: How about it’s chassis? A: It’s electronically controlled six-speed automatic transmission with manual shift mode, four-wheel independent suspension and front and rear disc brake all prove it is quite a good car . B: I like it very much. What's the price? A: The price is RMB 240,000. B: Any discount? A: Well, this is the newest model and very popular. I think it’s worthy. B: Ok, I will take it. A: Thank you.

10. New words engine [endʒin] n. 发动机,引擎 mechanics [mikæniks] n. 力学, 机械学, 机件 automobile [ɔ:təməbi:l] n. 汽车 vehicle [vi:kl] n. 交通工具, 车辆 gasoline [ɡæsəli:n] n. 汽油 combustion [kəmbʌstʃən] n. 燃烧, 烧毁 chamber [tʃeimbə] n. 房间，室 piston [pistən] n.〈机〉活塞 crankshaft [kræŋkʃɑ:ft] n. 曲轴 diesel [di:zəl] n. 柴油 reciprocating [risiprəkeitiŋ] adj. 往复的,来回的,交替的 torque [tɔ:k] n. (尤指机器的)扭转力 cylinder [silində] n. 圆筒, 圆柱体，气缸 discharge [distʃɑ:dʒ] vt. & vi. 放出; 流出 n. 排放出的物体 pump [pʌmp] n. 泵, 打气筒 vt. & vi. 用抽水机汲水, 给…打气

11. New words tank [tæŋk] n. 油[水]箱, 罐, 槽 carburetor [kɑ:bjuretə] n. 〈机〉化油器 deliver [dilivə] vt. & vi. 递送, 交付 feedback [fi:dbæk] n. 反馈, 反馈信息 voltage [vəultidʒ] n. 电压, 伏特数 circulate [sə:kjuleit] vt. & vi. (使)循环, (使)流通, 散布, 传播 coolant [ku:lənt] n. 冷冻剂,冷却液,散热剂 radiator [reidieitə] n. 汽车引擎的冷却器, 散热器 wear [wɛə] n. 穿,衣服,磨损 vt. 穿着,磨成 vi. 磨损,变旧,用坏 revolution [revəlu:ʃən] n. 革命,彻底改变,旋转 camshaft [kæmʃɑ:ft] n. 凸轮轴 vacuum [vækjuəm] n. 真空, 空间, 空虚 vt. 用真空吸尘器清扫 approximately [əprɔksimətli] adv. 近似地,大约 pound [paund] n. 磅, 英镑 vt. & vi. 连续重击

12. Phrases and Expressions internal-combustion engine 内燃机 heat energy 热能 mechanical energy 机械能 connecting rod 连杆 piston crank mechanism 连杆机构 valve mechanism 配气机构 fuel system 燃油供给系统 ignition system 点火系统 starting system 起动系统 cooling system 冷却系统 lubricating system 润滑系统 In accordance with 根据，按照 intake valve 进气门 exhaust valve 排气门 emission-related 与排放相关的

13. Phrases and Expressions electronic fuel injection (EFI) 电子控制燃油喷射系统 four-stroke-cycle gasoline engine 四冲程汽油机 top dead center（TDC） 上止点 bottom dead center（BDC） 下止点 intake stroke 进气行程 compression stroke 压缩行程 power stroke 做功行程 exhaust stroke 排气行程 atmospheric pressure 大气压力 starter motor 起动机 ignition key 点火开关 spark plug 火花塞 compression ratio 压缩比 abnormal noise 异响 piston slap 活塞敲击

14. Thank You !